I believe campaign managers will be the best to answer this question, I will like campaign managers to give some valid reasons they are not yet using lightning network for paying, also people can comment about any suggested reasons they are thinking to be the reason.
I felt the need today. I am managing a campaign where I was suppose to pay 50+ users in bitcoin. Total amount was something like 0.004 BTC and Electrum was suggesting me a fee of 0.00435457 BTC
Fees for broadcasting 0.00435457 BTC ( 255.4 sat/byte ) at current sat/byte rate for next block.
This is obviously unreasonable. So I had to change the payment method. With that I am now in some hassle.
1. I had to move the campaign thread from Service board to Altcoin board.
2. Asking LTC address from the participants and many more.
I think in the next BTC paying campaign I will consider an LN payment if I can convince the devs of whatever the project is. One problem I see is the wallet making hassle for campaign participants. Do we have a topic about creating LN channel using Electrum?